The G3 format is used to compress image files in TIFF format when sending faxes. The compression algorithm allows for the use of a standard 10-times compression, which can be increased. It is used to remove excess image data, which makes it possible to reduce the size of the image and speed up delivery.
This format was used to store bitmap and vector images natively on Macintosh computers. It was used for laying out and sharing images between programs. It used JPEG compression algorithms and RLE encoding. Today, the PICT format is used in the Windows environment with the PCT extension.